This invention relates to a process for preparing compounds having anti-androgen activity. Androgens are substances which are active in stimulating secondary sex characteristics in males. Although such substances obviously are of great physiological significance, they can produce certain undesirable side effects, and it would be highly advantageous to prophylactically or therapeutically eliminate or minimize these effects. For example, the stimulatory effects of androgens upon the prostate gland have been known for many years. The pathogenesis of benign prostatic hypertrophy (BPH) and/or prostatic cancer (PC) is not fully understood; however, it is thought that both of these syndromes are subject to the influence of androgens. In addition, acne, an inflammatory disease involving the sebaceous glands and found chiefly in adolescents, is thought to be dependent upon sebum secretion which, in turn, is dependent upon androgen action.
Androgens are steroidal hormonal agents. For some time, it has been customary to attempt control of androgen activity by administration of other steroids. However, although administration of these steroids may be effective in diminishing androgen action, their administration, in general, results in other unwanted side effects which limit their usefulness.
Recently, a class of compounds has been discovered which are non-steroidal in structure and which exhibit potent anti-androgen activity. These compounds are dihydrobenzopyranoxanthenones and hexahydrobenzopyranoxanthenones. In general, the latter are prepared by hydrogenation of the former. One of the methods for effecting this reduction constitutes the process of this invention. The process of this invention involves the electrolytic reduction of a dihydrobenzopyranoxanthenone to its corresponding hexahydrobenzopyranoxanthenone. The method of this invention, by appropriate selection of reaction conditions, provides unique direction and control of the stereoconfiguration of the hexahydro product which is formed.